What Are Some Suggestions On Repairing Scratches On The Back Of The Iphone

I have an LRG case so a gel cover will not help me in this situation. I just want to repair the scratches somehow w/o getting a new case or paying the 250 replacement fee to apple. I want the scratches gone as best as possible w/o spending a ton of money. Has anyone fixed their iphone scratches on the back of their phone ?